Method of making glass-ceramic laser gyroscope frame

Abstract

This invention provides a method for forming ring laser gyroscope frames without extensive machining. Parts of necessary configurations for such frames are so fashioned that they can be sealed together into a unit. Those parts are prepared from very low expansion glass-ceramics of particular compositions and are sealed together with low expansion, thermally devitrifiable sealing glasses, also of particular compositions.

I claim: 
     
       1. A method for making ring laser gyroscope frames by sealing individual preformed members into an integral body which comprises the following steps: (1) forming members of predetermined configuration from glass-ceramics exhibiting a linear coefficient of thermal expansion of less than 1×10 -7  /°C. within the temperature range of from -50° C. to +100° C., said members consisting essentially, expressed in terms of weight percent on the oxide basis, of   ______________________________________                                    
SiO.sub.2                                                                 
          64-67      ZnO        0.7-4.2                                   
Al.sub.2 O.sub.3                                                          
         21-24       TiO.sub.2   2.0-3.25                                 
Li.sub.2 O                                                                
         2.6-3.7     ZrO.sub.2  1.25-2.5                                  
MgO      0.1-1.5     TiO.sub.2 + ZrO.sub.2                                
                                  4-5.25                                  
BaO      0-1         As.sub.2 O.sub.3                                     
                                0-1                                       
______________________________________                                    
       (2) applying a coating of a thermally devitrifiable frit consisting essentially, expressed in terms of weight percent on the oxide basis, of 62-68% PbO, 12-20% TiO 2 , 12-18% SiO 2 , 1-3% Al 2  O 3 , and 1-3% B 2  O 3  onto the surfaces of said members to be sealed together;   (3) bringing the frit coated surfaces of said members into contact with one another;   (4) heating at least the frit coated contacting surfaces of said members to a temperature between about 700°-800° C. for a period of time sufficient to effect a fusion seal between the contacting surfaces, thereby forming an integral body, and to cause the in situ crystallization of lead titanate crystals having a perovskite structure in said seal, such that said seal exhibits a linear coefficient of thermal expansion of less than 30×10 -7  /°C. within the temperature range of from 0° to 300° C.; and then   (5) cooling the integral body to room temperature.   
     
     
       2. A method according to claim 1 wherein said glass-ceramic has the approximate composition by weight percent of   ______________________________________                                    
SiO.sub.2                                                                 
        65.9      MgO    1.3    TiO.sub.2                                 
                                      2.7                                 
Al.sub.2 O.sub.3                                                          
        21.7      BaO    0.8    ZrO.sub.2                                 
                                      1.7                                 
Li.sub.2 O                                                                
        3.3       ZnO    1.6    As.sub.2 O.sub.3                          
                                       0.7.                               
______________________________________                                    
     
     
     
       3. A method according to claim 1 wherein said thermally devitrifiable frit has an approximate composition by weight percent selected from the group consisting of   ______________________________________                                    
       PbO     64                PbO   65.3                               
       TiO.sub.2                                                          
               16                TiO.sub.2                                
                                       18.1                               
I      SiO.sub.2                                                          
               16        and II  SiO.sub.2                                
                                       12.4                               
       Al.sub.2 O.sub.3                                                   
               2                 Al.sub.2 O.sub.3                         
                                       1.98                               
       B.sub.2 O.sub.3                                                    
               2                 B.sub.2 O.sub.3                          
                                       1.57                               
______________________________________                                    
     
     
     
       4. A method according to claim 1 wherein said period of time sufficient to effect a fusion seal and cause in situ crystallization ranges from about 025 to 3 hours.